1. Prior Packaging Techniques PA0 2. U.S. Application Ser. No. 893,324
This invention is in the field of packaging and is more specifically directed to a new and improved method and apparatus for wrapping a package with plastic film material so as to provide a strong and protective enclosure of the package in an economical manner. The term "package" as used herein is employed in its broadest generic sense and can comprise a plurality of bags, bundles, rolls, cans, or the like which are desired to be associated together in a unitary grouping or a single such bag or similar item about which it is desired to provide a protective wrapping or covering. For example, the finished package provided by the inventive apparatus and method can consist of a plurality of bags such as bags of dog food, potting soil, books, newspapers, underwear or the like. Other examples of items capable of being associated together by the inventive apparatus and method into a unitary package includes tubes, cartons, cans and rolls which are wrapped together by the inventive apparatus and method to provide a unitized package consisting of a desired plurality of the particular items being wrapped.
Recognition of the foregoing problems has resulted in a number of both fully automatic and manual rotational wrapping machines which are used for wrapping items with a thermoset film paper, netting, etc. in a variety of ways. Unfortunately, the known wrapping machines suffer from a lack of versatility in that they are capable of usage for wrapping only products within a relatively narrow range of dimensional configurations. In other words, many of the machines will only wrap a particular type and size of item such as a boxed or pallet mounted item and are incapable of usage for wrapping other items having a different nature, configuration and/or dimensions. Another disadvantage of the prior known wrapping machines resides in the fact that they effect the wrapping operation by rotating the items being wrapped about a vertical axis or push them through a web tunnel which results in poor web tension and a single wrap. One of the problems of many machines arises from the fact that items being wrapped are always maintained in an unchanging fixed vertical orientation; consequently, if the items consist of bags or the like containing powdered or similar materials which tend to settle, the bags will bulge outwardly at their bottom portions so as to result in a non-symmetric finished package which is both aesthetically unattractive and functionally deficient in not being capable of being easily stacked or stored. Another shortcoming of many conventional machines is that they present safety hazards to the operator in that clothing or the like of the operator can be engaged by the moving parts to inflict serious injury or death of the operator.
In copending U.S. Application Ser. No. 893,324, there is described a plastic film wrapping apparatus having clamping means consisting of two vertically spaced parallel banks of horizontal tines which receive the items to form the package between the two tine banks. The upper tine bank then moves toward the items to be wrapped which are supported on the lower tine bank to clamp and hold the items between the tine banks for rotation about a horizontal axis during the wrapping of the package with wrapping material from a supply roll. The package components are rotated to continuously invert them during the wrapping operation and are not permitted to settle and/or distort the finished package.
The package resultant from the invention of copending U.S. Application Ser. No. 893,324 is that it is aesthetically attractive, permits visual inspection of its contents when desired and is of generally square or rectangular configuration and compacted so as to be easily stacked or stored with similar packages. Moreover, the resultant package provides a substantial energy cost savings over cardboard boxes, bagging, or shrink wrapping. In such manual machines, there is a safety feature which is a pivotally mounted guard shield adjacent the area in which the package components are wrapped; the guard shield has an opening through which the package components are moved for positioning on the lower tine bank. Prior to the commencement of rotation of the package components to begin a wrapping operation, the guard shield swings outwardly to insure that the operator is clear of the machine and cannot possibly be injured by this operation.
In U.S. Application Ser. No. 893,324, there is shown a machine frame supporting a horizontal main drive shaft mounted for rotation about its axis and having a vertical turret plate mounted at one end with a fixedly attached first bank of horizontal clamp and support tines fixedly attached to and extending from the turret plate and a second bank of movable horizontal clamp tines on the turret plates mounted for movement toward or away from the bank of fixedly attached tines on the turret plate. The area between the two tine banks comprises a loading and wrapping station for the package components to be wrapped in that a stack of bags or other package components is positioned on the fixedly attached tines, which are always in a lower position below the movable bank of tines when the turret is stopped at the end of a cycle in a loading position. Clamp cylinder means on the turret are provided with a pressurized work fluid such as compressed air for moving the uppermost movable bank of tine members downwardly to clamp the package components together against the lower bank of tines to hold the package components for subsequent rotation of the turret and the clamped components about the horizontal axis of rotation of the main drive shaft. Such clamping of the end of a web of thermoplastic wrap material extending from a supply roll of such material on the machine frame against the uppermost package component. Consequently, rotation of the package components serves to wrap the web of thermoplastic material about the package components with the number of wraps depending upon the number of rotations of the main drive shaft. Rotation of the turret is stopped automatically after a predetermined number of rotations and a transversely movable carriage, mounted for reciprocation perpendicularly to the axis of rotation of the main drive shaft toward and away from the loading station, is moved forward toward the wrapped package in the station. A hot cutter knife mounted on the carriage consequently engages the taut web of wrapping material extending from the package up to the supply roll to sever the web immediately and a presser plate on the carriage moves against the web end below the hot cutter knife just prior to engagement of the web by the knife and serves to smooth out and press the web end against the underlying thermoplastic wrapping to bond it thereto and provide a finished package; a nonheated web cutter knife can be optionally employed if desired.
The carriage is then moved back from the package and pressure by the tines on the finished package component P is released to permit a pusher plate mounted on the turret adjacent one end of the package to be actuated to discharge the completed package by stripping it outwardly along and from the tines.
The guard shield is then automatically returned to its inner closed position and the apparatus is then ready for a subsequent loading of package components. An air curtain provided by a plurality of air jets in a manifold on the carriage blows the severed end of the web extending from the supply roll upwardly above the loading area in which the next stack of components are to be positioned so that downward movement of the upper tine bank clamps the web end to the stacked package components and subsequent rotation of the package components and tines unreels the web from the roll by wrapping the web about the package components.
In an alternative embodiment shown in U.S. Patent Application Ser. No. 893,324, a fluid power cylinder on the carriage has an elasometric pusher member on its rod which is extended prior to loading to engage the web end for providing a mechanical positioning of the web end above the package components beneath the upper tine banks in addition to the positioning by the air curtain.